Corrugated web materials are well known in the art to be used in various applications as a material as such or as a component in the manufacturing of articles. In order to arrive at such webs, essentially flat raw materials are supplied to a process which three-dimensionally shapes such corrugations. Corrugated web material yield a wide variety of benefits including low-density for a desired stability, but also can provide good softness. Typical corrugation materials include sheets, films, foams, and the like, as well as woven or nonwoven materials.
When corrugated materials are used in the manufacture of articles, the corrugated shape can be created during this manufacturing process (“on-line”) or separately, such as “off-line” shaping with subsequent shipment or transport to this manufacturing site. Due to the voluminous configuration, the “on-line” process is often preferred.
There exist in the art processes for forming corrugation of materials such as for example U.S. Pat. No. 4,806,300 (Walton et al.). During such processes, the materials are corrugated by being fed through two interpenetrating corrugated rolls. This procedure, however, leads to stretching of the material and potentially to plastic deformation in the transverse direction. In turn, such stretching and plastic deformation may change the physical structure of the material and hence its properties.
U.S. Pat. No. 5,906,879 describes a ultra-resilient three-dimensional non-woven fiber material, wherein the shape is maintained by means of a heat-activatable adhesive component incorporated into the structure. WO 96/00625 (Raidel et al) describes the forming of corrugations by means of a guide bed, and co-pending EP-application 99 12 46 37 (Dziezok et al., filed Dec. 19, 1999, case attorney docket number CM02251FQ) discloses a process for forming longitudinal corrugations in a web material by means of intermeshing groove rolls. In both cases, the corrugations are formed in longitudinal direction of the web while the web is not restricted in transverse direction, such that the overall width of the web is reduced. After the corrugations are formed, they are stabilized by an added component, such as adhesive stabilization within the web as in the above mentioned US'879, by attaching a flat support web to the corrugations, or by plastically deforming the web along the lines of corrugation.